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      1 /*
      2  * Copyright 2015 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #include "gm.h"
      9 #include "SkPath.h"
     10 
     11 DEF_SIMPLE_GM(PlusMergesAA, canvas, 256, 256) {
     12     SkPaint p;
     13     p.setColor(SK_ColorRED);
     14     p.setAntiAlias(true);  //  <-- crucial to the test that we use AA
     15 
     16     // Draw a two red squares.
     17     canvas->drawRect(SkRect::MakeWH(100, 100), p);
     18     canvas->drawRect(SkRect::MakeXYWH(150, 0, 100, 100), p);
     19 
     20     p.setColor(0xf000ff00);
     21 
     22     // We'll draw a green square on top of each using two triangles.
     23     SkPath upperLeft;
     24     upperLeft.lineTo(100, 0);
     25     upperLeft.lineTo(0, 100);
     26     upperLeft.lineTo(0, 0);
     27 
     28     SkPath bottomRight;
     29     bottomRight.moveTo(100, 0);
     30     bottomRight.lineTo(100, 100);
     31     bottomRight.lineTo(0, 100);
     32     bottomRight.lineTo(100, 0);
     33 
     34     // The left square is drawn simply with SrcOver.  It will show a red seam.
     35     canvas->drawPath(upperLeft, p);
     36     canvas->drawPath(bottomRight, p);
     37 
     38     // Using Plus on the right should merge the AA of seam together completely covering the red.
     39     canvas->saveLayer(nullptr, nullptr);
     40       p.setBlendMode(SkBlendMode::kPlus);
     41       canvas->translate(150, 0);
     42       canvas->drawPath(upperLeft, p);
     43       canvas->drawPath(bottomRight, p);
     44     canvas->restore();
     45 }
     46